This section is intended to provide a background or context to the invention that is, inter alia, recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
For industrial, commercial, and residential applications, consumers demand more complicated lighting systems, while also desiring flexibility and adaptability. However, the general look, feel and physical construction of overhead ceiling lighting systems around the world have not changed appreciably in the last 50 years. Industrial overhead lighting, whether in high-rise office buildings, factories, or industrial office parks has been and still is typified by regular lines of cumbersome high power down lighting fixtures mounted within (or hanging through) openings or clearances made in the lightweight decorative (sound absorbing) ceiling panels surrounding them. Each present day down lighting fixture is typically designed to illuminate about 36 square feet on the floor below, which requires about 4000 lumens to do so to general standards (500-1000 Lux illuminance). High voltage (ac) electrical power is applied to large groups of these high light output lighting fixtures at the same time using expensive high voltage cabling and conduits. The fixtures appear from below as physically bright areas of light and glare. Energy waste due to fixture inefficiency and their substantial amounts of misdirected light is enormous. Dimming the conventional light bulb types that are in common practice is inefficient, and not generally applied, cutting off an attractive means of energy conservation. Floor and wall areas not needing light are often lighted anyway, and areas only needing partial lighting are often lighted fully.
No remotely similar system is deployable using conventional lighting practices and conventional lighting hardware. Ceiling panel materials are typically 0.5-0.75 inches thick and quite fragile in their construction. Classical lighting fixtures and luminaires are simply too thick and too heavy to be embedded in such materials, whether at time of manufacture or installation. Embedding high voltage power lines in conventional ceiling material is discouraged by Governmental safety regulations and by incompatibilities in the way the classical lighting fixtures are installed and mounted.
Low voltage lighting fixtures based on the semiconductor light emitting diode (LED) have been attracting market interest lately primarily because of their potential for improved energy efficiency, their low voltage DC operation, their freedom from hazardous materials like Hg, their lack of infrared and UV radiation, their ease of dimming, their ease of color adjustment, and their long service life. For a variety of reasons, almost all early commercial emphasis is being placed on LED lighting treatments that directly replace (and imitate) existing light bulbs, whether as screw-in bulb alternatives, or in fixture formats that even more deliberately imitate and thereby substitute for the existing fluorescent troffers and recessed down-lighting can form factors. As it's turning out, however, the early LED fixture substitutions are only somewhat lighter in weight and only somewhat more compact than their traditionally cumbersome light bulb counterparts.
Semiconductor LEDs are chosen for all practical examples of embedded luminaires in the present invention for much the same reasons, but more relevantly to the invention herein for the need to exploit their intrinsic compactness. Over time, other suitable luminaire types may emerge based on organic LEDs (referred to as OLED), thin flat fluorescent sources, flat micro plasma discharge sources and electron stimulated luminescence (referred to as ESL), to mention a few.
While LEDs generally satisfy the present invention's need for thinness, in one embodiment, applying LED light sources in accordance with the present invention requires a degree of adaptation from prior art LEDs. Preferable luminaire configurations need fit substantially within the prevailing ceiling tile cross-section, mated with interconnected low-voltage DC power conducting busses, electronic power control components and light sensing components. Power conducting busses and various integrated electronic component elements are typically thin in cross-section, but arranging comparably thin LED luminaires with acceptably distinct down-lighting illumination patterns has not previously been done.
Bare semiconductor LED emitters could be embedded in ceiling material bodies according to the present invention, but doing so would provide few advantages. Not only would light emission spread undesirably in all angular directions, but also LED brightness would simply be too high to risk human exposure to accidental direct view.
A number of prior art arrangements combining LEDs with secondary optics (e.g., lenses, reflectors and diffusers) could also be embedded in the body of ceiling materials according to the present invention. While doing so is described in some detail below, no known prior art arrangements adequately mask direct view of the LEDs' extraordinarily high brightness level (sometimes 200 times greater than the brightest commercially available light bulb fixture) without destroying the LEDs' corresponding energy efficiency, creating off-angle glare, or both.
A few new examples of embeddable luminaires adapting prior art LED combinations are introduced below that successfully dilute the LED brightness visible to observers, while also achieving more distinct illumination patterns, smaller loss of energy efficiency and reduced glare.
Exemplary embodiment of luminaires for the present invention are taken from U.S. Provisional Patent Application Ser. No. 61/024,814 (International Stage Patent Application Serial Number PCT/US2009/000575) entitled Thin Illumination System, and to a lesser extent from issued U.S. Pat. No. 7,072,096 (entitled Uniform Illumination System) and U.S. Pat. No. 6,871,982, U.S. Pat. No. 7,210,806, 2007-0211449 (entitled High Density Illumination System). These luminaire examples combine reduced viewing brightness and glare reduction with simple means for changing the luminaires beam pattern (shape and angular coverage). They apply new combinations of LEDs with efficient forms of angle transforming couplers, light guide plates with light redirecting films, and beam width adjusting films.
Embedding a thoughtful distribution of luminaires within the thin materials of an overhead lighting system has additional advantages in energy conservation, in enabling more sophisticated forms of lighting control, and in reductions in cost of ownership associated with simplified infrastructure.
Energy conservation opportunities are enabled in the present invention by its capacity to use and separately control the illumination from a larger number of lighting fixtures per unit area than is common practice. With more lighting sources under control, floor and wall areas may be illuminated according to need.
Lighting systems have previously been used that provide some minor level of control to a user. Prior art examples of commercial lighting systems embodying a form of implied networking and programmatic control may include those used in the switching of stage and theatrical lighting luminaires, and those used in keypad control of broader home management systems integrating control of security, heating and cooling, window shades, watering systems and home entertainment, in addition to indoor and outdoor lighting. Those particular networks interconnect and control discretely powered appliances mounted on a wide variety of supporting structures in a wide variety of locations with little reduction in wiring and infrastructure complexity.
Aside from these network-based attributes, the embedded nature of overhead lighting systems based on the present invention enable a distinctive new look or visual appearance to both lighted and unlighted ceilings. This distinctive look may be varied geometrically according to the artistic choices of lighting architects and building contractors involved, but is generally set forth by smaller square, rectangular and circular lighting apertures than has become traditional, each being less conspicuous, lower in glare and more finely distributed per unit ceiling area than is present practice. Lighting apertures are of similar appearance throughout the integrated ceiling systems whether providing general flood lighting, task lighting, spot lighting or wall washing as needed.
These unobtrusive lighting apertures resemble those drywall installations where conventional lighting fixture apertures are cemented to the drywall cutout right on the job site. Lighting fixtures that enable this practice are referred to as being mudded in. Significant on site finishing labor is required to match ceiling material to lighting fixture.